PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



25 



which they occasionally entered, but using the feet in digging and excavating for 

 food. Invariably animals using the feet as propelling paddles have the propodials 

 more or less elongated, while in tail-propelling animals not only the propodials 

 but the epipodials are shortened and the digits elongated. In none of these groups 

 will the cotylosaurs enter. Upon the whole it seems to us that the habits of these 

 animals may have most nearly approximated the present habits of the marsh 

 turtles. 



The pelvis is very nearly perfect. The crest of the ilium of the left side is 

 broken away and the median portion of the pubis is slightly injured, otherwise 

 the bones of both sides are complete. As in the rest of the skeleton the nature 

 of the bones makes it impossible to trace the sutures. The crest of the ilium is 

 elongate antero-posteriorly, with the posterior end somewhat higher than the 

 anterior, so that the upper line slants downward and forward. The upper edge is 

 thin, but 2 or 3 centimeters below the crest there is a sudden thickening, forming 

 a distinct shelf with a nearly horizontal upper surface. The posterior end is formed 



Fig. 13. — Diasparaclus zenos Case, X>^. A, right side of pelvis; B, lower view of pelvis; C, anterior 

 view of pelvis; face of sacral vertebra somewhat restored. 



by a thickened process, about a centimeter wide, which is the direct continuation 

 of the shelf mentioned. Below the shelf the ilium contracts rapidly until it is 

 less than half as wide as the crest. The acetabulum is of the form common in the 

 Cotylosauria, rather shallow and longer than high. The anterior edge is not well 

 defined, but posteriorly there is an elevation of the rim on the proximal portion 

 of the ischium forming a buttress for the head of the femur. Above, there is the 

 usual tuberosity on the iliimi at about the middle of the upper line of the cavity. 

 The pubis is shorter than the ischium. The anterior edge, opposite the ace- 

 tabulum, is convex, but toward the lower end the edge becomes wider and the bone 

 is turned so that it is nearly horizontal. The anterior end is thickened with an 

 elongate, flat, oval face indicative of the presence of a prepubic bone as suggested 

 by Broili. The lower portion of the bone is nearly flat (fig. 13 b), but towards the 

 median line it is turned sharply down and, in union with the bone of the opposite side, 

 forms a deep symphysis indicated on the outer surface by a prominent keel. The 

 pubic foramen lies just below the anterior end of the acetabulum, it penetrates 

 the bone directly, passing slightly upward and forward to open on the flat anterior 

 face described below. Viewed from the front, the cavity of the pelvis is slightly 



